Catalytic cracking process with the production of high octane gasoline



States 3,065,166 CATALYTIC CRACKENG PRQCESS WETH THE P220 DUCTIN DI? HGHCTANE Harvey Hennig, Crystal Lake, lli., assigner to The Pure OilCompany, Chicago, lil., a corperation of @hin Filed Nov. I3, 1959, Ser.No. 852,738 S Claims. (Cl. 20S-67) The present invention relates to aprocess for converting hydrocarbon oil into substantial yields of highoctane gasoline, and, more particularly, it relates to a method ofconverting cracking stocks in a'fluidized cracking system, using thecirculating-catalyst type of operation, wherein utilization is made ofthe heat content of the freshly regenerated catalyst as it leaves theregeneration zone, that is, before contact with incoming fresh feed, tosupply the heat required to crack a mixture of a hydrogenated heavyrecycle gasoline fraction and a heavy straight-run naphtha fraction (themixture boiling in the range of about 350-425 F., either hydrogenated ornot), said heat supply being provided in a transfer-line reactor at atemperature above those maintained in the main cracking zone. In anotheraspect of the invention, a heavy gas-oil fraction boiling in the rangeof about 460 to 800 F. is recovered from the fractionator, separatelyhydrogenated at about 600 to 800 F. and mixed with a hydrogenatedrecycle gasoline fraction having a boiling range of about 350-425 F.,and the mixture is separately preheated to a temperature of about 450 to800 F. and sent to said transfer-line reactor. In still anotherembodiment of the invention, the afore-mentioned mixture is mixed with aheaVy-straight-run naphtha, having a boiling range of about 350 to 425F., prior to preheating and transfer to said transfer-line reactor.Another variation of the invention comprises the process in which saidheavy gas-oil and heavy recycle gasoline fractions are preheated andsent in admixture to a common hydrogenation reactor and the hydrogenatedmixture is preheated and sent to said transfer-line reactor. In stillanother embodiment the heavy gasoline fraction is hydrogenated and sentto the catalyst transfer-line during the reaction. In still a furtherembodiment of the invention the heavy gasoline fraction may be separatedinto two parts and one part thereof hydrogenated and recycled with theunhydrogenated remainder. The invention also includes as another featureof this latter step the additional feature f adding a heavy straight-runnaphtha to the recycled portions returning to the reactor. Thisinvention is an improvement over the process disclosed in United StatesPatent 2,890,164, dated June 9, 1959, by Byron B. Woertz.

In the Woertz patent it is stated that modern internal combustionengines with ever-increasing compression ratios and power outputsrequire `gasolines which burn quickly and efficiently, leaving a minimumof carbonaceous deposits in the combustion chamber. It is now known thatcertain heavy gasoline ends are responsible for much of the spark-plugfouling experienced today. Refiners have employed several expedientsdirected to overcoming this problem, including adjustment of thecracking conditions to fit the inherent characteristics of the chargestock, and recycling certain fractions of the products to the mainreaction zone. Thus, a feed hydrocarbon oil may be subjected tofractionation into light, medium, and heavy fractions, and each fractionseparately subjected to cracking conditions optimum for the hydrocarbonsconcerned. In other methods, intermediate conversionv products areseparated from the cracked products in a fractionation zone and recycledback to the incoming charge-oil line wherein they are mixed directlywith partially reactivated catalyst or catalyst which has been subjectedto complete regeneration. In still other methods, the intermediateboiling fractions from the cracked products are subjected to cracking ina separate cracking zone using a portion of regenerated catalyst, andthe products are either transmitted to a common fractionator, orseparately fractioned.

The crude gasoline fractions resulting from the cracking of heaviercrude oil fraction, such as virgin gas-oil, contain certain heavygasoline ends, that is, material boiling between about 35 0425 F., whichare thermally stable and resistant to further cracking in the mainreaction zone. In accordance with my invention, an additional advantageis gained through hydrogenating this material boiling between about35S-425 F., prior to separate contact with hot, regenerated catalyst,just prior to the entrance therein of the main oil charge. Heavy recyclegasoline fractions are separated from the cracked products, hydrogenatedunder conditions established to reduce the olefin content and partiallysaturate the aromatics, and the hydrogenated product is recycled to ahot catalyst transfer-line suiciently far upstream from the point atwhich the fresh feed is charged to accomplish substantial cracking ofthe hydrogenated product between the points of feed entry.

As normally initially produced, the said heavy gasoline fraction mayamount to about 4 to 10 volume percent of the fresh feed. If recycledwithout hydrogenation and in the conventional manner with the freshfeed, so little cracking takes place that the heavy recycle gasolineaccnmulates up to an extent of about 20 to 40 volume percent, based onfresh feed. The combination of hydrogenation and reaction in thetransfer-line reactor, in accordance with this invention, cracks therecycle gasoline fraction to such an extent that only about 10 to 25volume percent, based on fresh feed, is recycled.

With the process of this invention, advantage is taken of the presenceof hot, regenerated catalyst particles Within the transfer line closerto the regenerator, the higherthan-reactor temperature prevailing in thecatalyst transfer-line, and the longer overall time of contact with thecatalyst (including the time within the transfer-line Zone, the time therecycled fraction is in contact with incoming oil and hot regeneratedcatalyst in the line leading t0 the reactor, and the time Within themain catalyst zone). Of prime importance is the transfer-linetemperature, which is in excess of reactor temperature. This process isapplicable to moving-bed, fluid-type catalytic cracking processes, orother circulating catalysts processes, including Thermofor catalyticcracking.

The principal object of this invention is to provide a process for theconversion of hydrocarbons in the presence of a suspended catalyst,wherein the hydrocarbons are caused to pass through a catalytic crackingzone, the cracked products are fractionated to yield (a) tail gas, (b) agasoline fraction of enhanced octane number, (c) a heavy gasolinefraction boiling in the range of about 350- 425 F., (d) a light gas-oilboiling above about 400 F., (e) a heavy cycle stock or gas oil boilingabove about 460 F., (f) a decanted oil, and, (g) a slurry oil. The heavygasoline fraction is separately hydrogenated, the hydrogenated productis preheated, if necessary, and sent to a transfer-line reactorconveying hot, regenerated catalyst to said reaction zone, and thecracked and hydrogenated products are mixed with incoming feed at theend of the transfer-line reactor and pass to the main reactor.

A further object'of this invention is to provide a process wherein theabove-mentioned heavy cycle stock or gas-oil fraction (e) is alsohydrogenated under separate conditions, and then is recycled with saidhydrogenated heavy gasoline fraction. It is to be understood that theheavy gasoline fraction (c) and the heavy gas-oil fraction (e) which arehydrogenated and recycled may be derived either from a single feed oilor from the cracked products of different feed oils, and may be used tosupplement the gasoline yield and octane number value obtained from feedoil from a second source. Likewise, the heavy gasoline ends, resultingafter separation of the desired product having an end point of about 350F., and obtained from the `combined cracked products of theafore-mentioned utilization of two-source feeds, may also behydrogenated and recycled in accordance with this invention. Inaddition, heavy straight-run naphtha from a different source may berecycled, with or without prior hydrogenation.

In general, the present invention comprises not only an improved methodof operating a catalytic cracking process wherein it is desired toproduce a gasoline having an endpoint of about 350 F., and whereineconomic loss and the necessity for changes in equipment are minimized,but it comprises amethod for utilizing the more thermally stable,heavier fractions and straight-run fractions to advantage inincreasingyields per pass, and in increasing the octane number of the lowerend-point product. This invention can be applied to any catalyticcracking process having particular application to continuous processesand will be described, although without being limited thereby, inconnection with a fluid-type operation using cross-how between a fluidreactor zone and a fluid catalyst regeneration zone. In these operationsthe reactor and regenerator conditions are selected in accordance withthe feed characteristics, the degree of cracking desired per pass, andthe desired character of the product. For purposes of this invention,reactor temperatures may range from above 750 F. to as high as 950 orl000 F., using atmospheric to superatmospheric pressures, and spacevelocities from 0.5 to l parts of oil per hour per part of catalyst.

The feed oil may comprise any hydrocarbon material capable of producinggasoline-boiling-range hydrocarbons on being subjected to crackingconditions. The feed oils may be obtained from various crudes, comprisethose hydrocarbons having boiling ranges between about 400 to l000 F.,and include such material as virgin gas-oils, heavy cycle stocks, andmixtures thereof, which, among other materials, are capable of producingheavy cracked gasoline hydrocarbons boiling in the range of 350 to 425F. for recycle in accordance with the invention. Preferred feeds aredistillates from Gulf Coast and Mid-Continent crudes which do not haveexcessive carbon contents, that is, the Conradson carbon residue shouldbe below about 1.0 weight percent.

The conditions used in regenerating the catalyst are designed to oxidizecarbonaceous materials and other combustible contaminants from thesurfaces of the catalyst particles and revivify the catalyst to itsoriginal activity. For this purpose, temperatures in the regenerationzone are generally higher than those in the reactor, being in the rangeof l000 `to 1250" 'F., with pressures comparable to those in thereactor, namely, atmospheric to superatmospheric. Any oxidizing mediummay be used, including air and other mixtures of oxygen and inert gases.The only limitation attaching to the regeneration conditions is thatthey must be more severe than the reactor conditions so that advantagecan be taken of the greater heat content of the regenerated catalyst.

Any suitable cracking catalyst may be used, such as bauxite, alumina,acid-treated kaolin, silica, fullers earth, acid-treated bentonite,diatomaceous earth, synthetic silicaalumina, and natural clays and thelike which are adapted to fluidization. These catalytic materials may beused singly or in admixture, and may include various known promoters.

In order to better explain the invention, reference is made to thedrawing which is a schematic iiow diagram showing one system applicableto the process. Only the essential reactors, vessels and conduits areshown in order that `one skilled in the art can follow the process andunderstand the invention more readily. Various pumps, gauges,pressure-control valves, temperatureand flowcontrol devices, etc., thatare required for actual operation have been omitted Hydrocarbon feed,which may be preheated su'ciently to vaporize a substantial portionthereof, is introduced into line E, through valve 2, wherein it mixeswith hot, regenerated catalyst.

The mixture of feed and catalyst passes to reactor 3 maintained undercracking conditions. A uidized reaction zone d is maintained with upperlevel 5 within reactor 33 by means of suitable space velocities andpressure controls well-known in the art. After suflicient residence timewithin zone 4t, the reaction products, some catalyst, and any unreactedfeed are withdrawn through line 6 into separator 7 wherein the entrainedcatalyst particles are separated by cyclonic action for return to thereaction zone through line 8. Reaction products and any remainingcatalyst lines pass through line 9 and enter separator 10 which removesmost of the remaining portion of catalyst lines and returns them to thereactor by line 11. Reaction products substantially freed from catalystnes pass through line l2 and valve i3 into fractionator 14 near thebottom. Fractionator lirimay be any type of fractionator suitable forfractional distillation, such as that shown iitted with plates l5, le,17 and 18, for the separation of the various fractions in accordancewith the characteristics of the reaction products.

A portion of the catalyst is separated from reaction zone ftand passedthrough line 19 and valve 20 into stripper 2l. Steam is introduced intostripper 21 at line 22. controlled by valve 23. Any entrained reactionproducts in the catalyst are conveyed by line 24 back to the reactor.Aerating steam may also be introduced in standpipe 25, through line 26and valve 27. Valve 23 in stand-pipe Z5 controls the ow of used catalystthrough line 29* into regenerator 30. Regenerator 30 may be an ordinaryfluid-type regenerator wherein air is introduced at line 3l, controlledby valve 32. The mixture of catalyst and air maintains a iluid bed 33,having an upper level 34 in regenerator 30, which is controlled by therates of iiow of material input and output in the regeneration zone. Therate of removal of regenerated catalyst is controlled by valve 35 instand-pipe 36. The mixture of combustion gases and catalyst withinregenerator 30 passes via line 37 into separator 38 wherein thecombustion gases from the regeneration are removed and conveyed from thesystem by line 39 and any entrained catalyst is returned to theregenerator by line 40. Hot regenerated catalyst leaving stand-pipe 36,controlled by valve 35, is continuously passed into injector 4l and isforced into transfer-line reactor 42.

Returning to fractionator lll-i, overhead materials comprising gas andgasoline fractions boiling up toV about 350 F., are removed by means ofline 45 and pass through condenser y446 into gas-liquid separator 47.Tail-gas is removed at line 48 and any water present (as a result ofsuperheated steam used to conduct the distillation) is collected in thebottom of separator 47 for withdrawal through line 50. Liquid gasolineproduct is withdrawn through 51 by pump 52. This product may be sent toa stabilizer (not shown) via line 53 and a part thereof may E thepresent invention and, accordingly, the boiling range of the originalfraction Withdrawn at line 59 should be checked, and if found to containcomponents boiling materially outside this range, it should berefractionated in a separate fractionator (not shown). The initialboiling point of this fraction may be as high as 375 F. but the endboiling point should not be over about 425 F.

Plate 16 serves to remove a light cycle stock boiling above about 400 F.This is sent through line 60 into stripper 6l operating by means ofsteam introduced in line 62. Light ends from this fraction are sent backto fractionator 14 by line 63 and the stripped light recycle stock iswithdrawn at line 64. The end point of the recycle stock is about 600 F.

Heavy recycle gas-oil, boiling above 460 F., is removed at plate 17 bymeans of line 65, and sent through heatadjusting coil 66 and valve 67 tohydrogenation reactor 68. Ordinarily, and for purposes of comparison ofthe results obtainable by this invention, heavy recycle gas-oil alone isrecycled via line 69 and pump 70 directly to join fresh feed entering inline 1.

A decanted oil stream is withdrawn from plate separator i8 through line71, and a slurry oil is withdrawn from the bottom of the fractionatorVia line 72, controlled by valve 73.

The heavy gasoline fraction withdrawn through line 59 passes throughheat-adjusting coil 74 and to valve 7S to hydrogcnation reactor 76.Hydrogenated product leaves reactor 68 via line 78 and reactor 76 vialine S0 and the combined stream passes via line 8l to gas-liquidseparator 82. Liquid from separator 82 passes into line 84, throughpreheater coil 85, by means of pump 86 and line 87 into injector 4l andreactor transfer line 42. Reactors 68 and 76 are arranged so that theymay be operated as two separate zones or as one common zone. Theoperation as two separate zones allows the application of ditferenthydrogenation conditions to the recycled fractions being treated.Operation of these reactors as a joint reactor allows the mixture ofheavy gasoline fraction (line 59) and heavy recycle gas oil (line 65) tobe treated to common hydrogenation conditions. By-pass line 8S,controlled by valves 89, is provided to by-pass reactor 76 and conveyall or part of the heavy gasoline fraction to line 84. Vessel 90 is usedto supply a heavy straight-run naphtha to the process by means of line91, controlled by valve 92 in accordance with one embodiment of theinvention. Gas-liquid separator 82 is provided to separate hydrogen fromthe liquid hydrogenated products from reactors 63 and 76. The separatedhydrogen gas leaves separator 82 by line 93, and is returned to reactors68 or 76 by compressor 94 and line 95 and branch lines 96 and 97controlled by valves 98 and 99. Make-up hydrogen is introduced throughline T00.

Conditions of hydrogenation in reactors 68 and 76 are maintainedsuiicient to reduce the oleiinic content and partially saturate thearomatic content of the respective feeds being treated therein. For thispurpose, temperatures of at least 600 F. at 400 p.s.i. with a minimumspace velocity of about 0.5 and a hydrogen to hydrocarbon ratio of aboutl-Z has been found to be necessary. Table l sets forth the range andspecific conditions for reactors 68 and 76 found applicable for purposeof obtaining substantially increased yields of high octane gasoline inaccordance with this invention.

Table I Reactor 76, Heavy Reactor 68 Heavy Gasoline Fraction Recycle fasOil Reactor Feed Condition Range Specific Range Specc Temperature, F60G-750 700 60G-800 725 Pressure, p.s.i 400-850 650 400-1, 000 700 Sp.Vel., Liq` VoL/VoL/Hr- 0. 5-4 1.5 0. 5-4 1.0 Hydrogen/Hydrocarbon moleratio 1-10 5 2-10 6 Catalyst Composition (for both) Rance Specific asCoO, Wt. percent 24 3 as M003, Wt. percent 8-15 12 Alumina (containing1-5% silica) balance The hydrogenated recycle fractions along with anyuntreated fractions from lines 38 or 9i enter injector 41 at atemperature of about 450 to 800 F. This temperature is adjusted by coil85. The regenerated catalyst is at a substantially higher temperaturethan the recycled fractions, making it possible to employ a minimumamount of heating in coil 35. The ratio of regenerated catalyst torecycled fractions in reactor line 42 is high so that substantiallycomplete Vaporization of the hydrocarbons occurs with very littlereduction in overall temperature.

The conditions within line 42 are maintained at regenerationtemperatures, or slightly lower, and the catalysthydrocarbon mixture issent therethrough at a linear velocity of about 6 to l0 feet per second,with residence times varying from about 0.5 to 5.0 seconds. Fluidizedconditions are maintained by sloping line 42 downwardly about l foot perevery l0 to 20 ft. in length. This allows a residence time suiicient topre-crack the hydrogenated recycled materials.

At the end of line 4Z, the reaction mixtures meets the incoming feed inpreheated condition in line 1, and the combined mixture passes intoreaction zone 4.

By proceeding in the manner described, the instant process exhibitscertain advantages over prior art methods. The hydrogenation of theolefnic content of the selected recycle stocks minimizes the tendency ofthe oletin Content of these stocks to crack and thus decreases theproduct content of olelins and more unsaturated products, which lead topolymers, gums and coke in the main reactor. Thus, the recycle stocksare slightly deactivated as far as their tendency to form coke isconcerned, and activated as far as their tendency to form gasolinehydrocarbons of high octane value is concerned. In addition, the olencontent of the finished gasoline is reduced without a correspondingreduction in octane number.

An additional feature of the process is that the hydrogenated recyclestocks are subjected to higher-thannormal reaction temperatures andcatalyst-to-oil ratios, thereby achieving greater cracking of the morerefractory components. The net results are more efficient use of heat,less catalyst fouling, higher catalyst activity in zone 4, and asuperior product distribution in comparison to that obtained if thetransfer-line reactor Were not used, or the hydrogenated recycle stockswere sent directly to zone 4. The following table of results illustratesthe various benets from my process.

Table Il Examhln I II HI IV V VI VII Feeds,v in volumes (liquid):

Fresh Feed-Virgin Gas Oil 100. 100. O 100. 0 100.0 Fresh Feed-HeavyStraight-Run Naphtha.. 10. 7 10. 7 10. 7 Recycle Heavy Gas Oil 40. 0 400 40.0

Recycle Heavy Gas Oil-Hydrogenated Recycle Heavy Gasoline Recycle HeavyGasolinefHydrogenated Total Feed 17S. 6 181. 2 176. 2.

Feed to Transfer-Line Reactor. 38. 6 41. 2 76. 2 Products:

Gas and Coke (Wt. Percent Fresh Virgin Gas Oil) 19. 3 20. 8 21.0 18. 822. 7 23. 3 20. 7 Butanes and Butylenes, Vol. Percent oi Fresh VirginGas Oil 16. 7 18. 0 18. 0 20.8 19. 9 19. 9 22. 7 Gasoline (350 F., E P)Vol Percent Fresh Virgin Gas Oil 140. 8 43.8 43. 6 45.5 47.8 47.4 49.5Gasoline (S-425 Percent Fresh Virgili Gas Oil 17. 6 Light Cycle Stock,Vol. Percent Fresh Virgin Gas il 1 22.0 24.3 24.4 21.7 27. 6 27. 7 25.0Heavy Oils, Vol. Percent Fresh Virgin Gas Oil 5.0 5.0 5.0 5.0 5.0 5.06.0

1 As normally fractionated, the products are:

Gasoline (400 F., E.

45.9 Vol. Percent.

Light Cycle Stock...

For comparison, Example'll shows results with typical normal operation,Without any of the embodiments of this invention.

Example II shows results with a heavy gasoline fraction which ishydrogenated and sent to catalyst transferline.

` Example lll shows the results from splitting the heavy gasolinefraction into two parts and hydrogenating only one part thereof, butrecycling both parts.

. Example lV, shows the results with a hydrogenated heavy gas-oilrecycle stocks and a hydrogenated heavy gasoline fraction.

Example V shows the results from the embodiment of Example II with theadditional feature of adding a heavy straight-run naphtha to thehydrogenatcd heavy gasoline fraction.

Example Vl shows the results from the embodiment of Example III with theadditional feature of adding a heavy straight-run naphtha to therecycled parts.

Example V11 shows the results from the embodiment of f Example 1V withthe additional feature of adding a heavy straight-run naphtha to thecombined hydrogenated stocks.

The examples demonstrate the increased gasoline yields that are madepossible through the process of this invention. Also, the volume percentlight cycle stock is increased. The temperature of the contact of therecycled fractions or recycled mixtures is maintained at about 100 to300 F. higher than the temperature of the incoming mixture and about 100to 300 F. higher than that prevailing in the main conversion zone 4 ofreactor 3. This temperature differential is subject to variation outsidethe 100 to 300 F., range for those feed stocks containing more or lessrefractory hydrocarbons. in general, the conditions set forth hereinwill apply to those feeds from which economical yields of gasoline canbe obtained. The only limitations applying to the invention appear inthe` appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In a catalytic cracking process wherein a hydrocarbon' oil having aboiling range of about 400 to 1000 F. is contacted with a crackingcatalyst at a temperature of above about 750 F. to about 1000" F. in aconversion zone, used catalyst and reaction products including agasoline fraction of enhanced octane number and an end boiling point ofabout 350 F. are separated, the improvement whereby gas and cokeformation are reduced and the yield of said gasoline fraction isincreased which comprises separating a heavy gasoline fraction boilingin the range of about 350 to 425 F. from said reaction prod- 24.5 Vol.Percent.

ucts, separately hydrogenating said heavy gasoline fraction at atemperature of about 600 to 750 F. at a pressure of about 400 to 850p.s.i. in the presence of a catalyst and about l to l0 mols of hydrogenper mol of stituents therein, mixing incoming feed hydrocarbon oil' withsaid cracked heavy gasoline fraction and regeneratedy catalyst andconducting the mixture to said conversion zone.

2. The process in accordance with claim 1 in which said reactionproducts from said conversion Zone are separated into a heavy recyclegas oil boiling above about 460 F., about 40 volumes of said heavyrecycle gas oil per volumes of feed hydrocarbon oil are mixed with saidincoming feed hydrocarbon oil and about 15.2 volumes of saidsubstantially saturated heavy gasoline fraction per 100 volumes of saidfeed` hydrocarbon oil are mixed with said hot regenerated catalyst insaid separate reaction zone.

3. The process in accordance with claim 2 in which about 8.1 volumes ofsaid substantially saturated heavy gasoline fraction and about 8.1volumes of untreated heavyV gasoline fraction per 100 volumes of feedhydrocarbon oil are'mixed with said hot regenerated catalyst in saidseparatereaction zone.

4. The process in accordance with claim 2 in which about 27.9 volumes ofsaid substantially saturated heavy gasoline fraction and about 10.7volumes-of a heavy straight-run naphtha per 100 volumes of feedhydrocarbon oil are mixed with said hot regenerated catalyst in saidseparate reaction zone.

5. The process in accordance with claim 4 in which about 20.6 volumes ofsaid substantially saturated heavy gasoline fraction and about 20.6volumes of untreated heavy gasoline fraction are mixed with said heavystraightrun naphtha passing into contact with said hot regeneratedcatalyst in said separate reaction zone.

6. The process in accordance with claim 1 in which said reactionproductsfrom said conversion zone are Vseparated into a heavy recyclegas oil boiling above about 460 F., said heavy recycle gas-oil fractionis hydrogenated at a temperature of about 600 to 800 F. atv a pressureof about 400 to 1000 p.s.i. in the presence of a catalyst and about 2 to10 mols of hydrogen per mol of said heavy recycle gas-oil fraction tosubstantially saturate the olen hydrogen content thereof and about 37volumes of the product along with about 15.8 volumes of saidsubstantially saturated heavy gasoline fraction per 100 volumes of feedhydrocarbon oil are mixed with hot regenerated catalyst in said separatereaction zone.

7. The process in accordance with claim 1 in which said reactionproducts from said conversion zone are separated into a heavy recyclegas oil boiling above about 460 F. and about 37 volumes of said heavyrecycle gas oil and about 15.8 volumes of said substantially saturatedheavy gasoline fraction per 100 volumes of said feed hydrocarbon oil aremixed with said hot regenerated catalyst in said separate reaction zone.

`8. The process in accordance with claim 7 in which said heavy recyclegas-oil fraction and said heavy gasoline fraction are combined andhydrogenated in a common hydrogenation zone.

References Cited in the file of this patent UNITED STATES PATENTS2,382,910 Pinkston Aug. 14, 1945 2,890,164 Woertz June 9, 1959 2,915,457Abbott et al. Dec. 1, 1959

1. IN A CATALYST CRACKING PROCESS WHEREIN A HYDROCARBON OIL HAVING ABOILING RANGE OF ABOUT 400* TO 1000*F. IS CONTACTED WITH A CRACKINGCATALYST AT A TEMPERATURE OF ABOVE ABOUT 750*F. TO ABOUT 1000*F. IN ACONVERSION ZONE, USED CATALYST AND REACTION PRODUCTS INCLUDING AGASOLINE FRACTION OF ENHANCED OCTANE NUMBER AND AN END BOILING POINT OFABOUT 350*F. ARE SEPERATED, THE IMPROVEMENT WHEREBY GAS AND COKEFORMATION ARE REDUCED AND THE YEILD OF SAID GASOLINE FRACTION ISINCREASED WHICH COMPRISES SEPARATING A HEAVY GASOLINE FRACTION BOILINGIN THE RANGE OF ABOUT 350* TO 425*F. FROM SAID REACTION PRODUCTS,SEPARATING HYDROGENATING SAID HEAVY GASOLINE FRACTION AT A TEMPERATUREOF ABOUT 600* TO 750*F. AT A PRESSURE OF ABOUT 400 TO 850 P.S.I. IN THEPRESENCE OF A CATALYST AND ABOUT 1 TO 10 MOLS OF HYDROGEN PER MOL OFSAID HEAVY GASOLINE FRACTION AT A MINIMUM SPACE VELOCITY OF ABOUT 0.5 TOSUBSTANTIALLY SATURATED THE OLEFIN HYDROCARBON CONTENT THEREOF,SEPARATELY REGENERATING SAID USED CATALYST AT A TEMPERATURE OF ABOVESAID REACTION TEMPERATURE TO PRODUCE REGENERATED CATALYST AT ATEMPERATURE OF ABOUT 1000* TO 1250*F., CONTACTING SAID SUBSTANTIALLYSATURATED HEAVY GASOLINE FRACTION WITH SAID HOT REGENERATED CATALYST FORABOUT 0.5 TO 5 SECONDS IN A SEPARTE REACTION ZONE TO INDUCE CRACKING OFTHE REFRACTORY CONSTITUENTS THEREIN, MIXING INCOMING FEED HYDROCARBONOIL WITH SAID CRACKED HEAVY GASOLINE FRACTION AND REGENERATED CATALYSTAND CONDUCING THE MIXTURE TO SAID CONVERSION ZONE.